There are a number of interesting phenomena that occur during an eclipse. One of the best is the "diamond ring" effect.

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At the beginning or end of the period of totality, you can see the corona all around the blacked out sun. Because the moon has tall mountains and deep valleys, sometimes the sun peeks through a valley at the start or end of totality. This effect looks like a diamond ring.

It is not safe to look at the diamond ring effect directly without eye protection since this is the sun showing and can cause eye damage.

Here is a video of the diamond ring effect at the end of a total eclipse...click HERE